The paper describes the original results of a comparative study of the standard seismic station vs. a novel interferometric sensor for civil engineering needs. The presented results showed that to implement seismic measurements using standard seismic stations, a method using a fiber optic interferometer may serve as an alternative. We presented time records and the frequency spectra obtained from experimental measurements of the dynamic response of the upper rock mass beneath passing tram vehicles (a total of 769 passes) over a period of five months of practical measurements under various climatic conditions. The fiber-optic sensor detected all phenomena at a 100% rate, and the recorded results were compared to the results from a standard seismic station. Both sets of results were recorded simultaneously and agreed significantly, especially in terms of frequency. With regard to time, all tram vehicle axles were detected in individual time records. With regard to frequency, the results detected in the bandwidth generally correlated to rail transport for individual types of tram vehicles.

New possibilities of vibration monitoring can be found in completely different physical approaches, where all measuring technology is currently based on sensors in the electrical domain. This paper presents two different promising alternative approaches to vibration measurement, specifically in the field of fiber-optics and pneumatic sensors. The proposed solution uses a Michelson fiber-optic interferometer designed without polarization fading and with operationally passive demodulation technique using three mutually phase-shifted optical outputs. Experimentally developed sensor systems for the registration of anthropogenic seismic phenomena were complemented by standard instrumentation for measuring seismicity used as a standard. The measurement was performed under simplified conditions using a calibrated stroke as a source of dynamic loading. In addition to alternative systems, the paper also presents the results of recalculation of the measured values in a time domain and basic relationships for the conversion to basic units derived from the SI (International System of Units) system and used internationally in the field of seismic engineering. The results presented demonstrate that even systems operating on a different physical principle have great potential to replace the existing seismic devices. The correlation coefficients for both sensory devices were high (above 0.9) and the average deviations from the measured values of the amplitude of the oscillation velocity did not exceed the value of 0.02, neither with the fiber-optic or pneumatic sensor.

At present, one of the primary tasks of the construction industry is to build transport infrastructure. This concerns both the construction of new bypasses of towns and the repair of existing roads, which are damaged by congestion, especially by freight transport. Whether it is a new building or a reconstruction, it is always very important to choose a suitable method of subsoil treatment. One of the most commonly used methods for soil treatment is currently compaction using vibratory rollers. This method is very effective both in terms of results and due to its low financial demands compared to other methods. Vibration is transmitted to the surrounding rock environment when compacting the subsoil using vibratory rollers. Although the intensity of these vibrations is not as pronounced as in other methods of subsoil treatment, such vibrations can have a significant effect, for example during compaction in urban areas or in an area with the presence of historical objects. Therefore, it is very advisable to monitor the effect of these vibrations on the environment during construction. This paper brings an original experimental comparative study of standard seismic instrumentation with a developed interferometric sensor for the field of monitoring vibrations generated during compaction of subsoil using vibrating rollers. The paper presents time and frequency domain results, as well as attenuation curves, which represent real attenuation of vibrations in a given rock environment. The results presented here show that a system operating on a different physical principle from the one used at present has the potential to replace the existing, very expensive, seismic equipment.

As the infrastructure grows, space on the surface in the urban area is diminishing, and the view of the builders is increasingly moving underground. Implementation of underground structures, however, presents a number of problems during construction. One of the primary side effects of tunnel excavation is vibration. These vibrations need to be monitored for potential damage to structures on the surface, and this monitoring is an integral part of any such structure. This paper brings an original pilot comparative study of standard seismic instrumentation with experimentally developed fiber-optic interferometric and acoustic systems for the purpose of monitoring vibration caused by the blasting operation. The results presented show that systems operating on physical principles (other than those previously used) have the potential to be an alternative that will replace the existing costly seismic equipment. The paper presents waveform images and frequency spectra from experimental measurements of the dynamic response of the rock environment, due to blasting operation performed shallowly during the tunnel excavation of a sewer collector. In the time and frequency domain, there is, by comparison, significant agreement both in the character of the waveform images (recording length, blasting operation timing) and in the spectra (bandwidth, dominant maxima).

Ground-borne vibration caused by mechanized construction works is the most common problem in built-up areas in general. In post-industrial cities, there are many building facilities in the category of brownfields. Parts of these buildings are often technically and culturally valuable buildings with varying degrees of decay. These are very susceptible to vibrations. The revitalization of brownfield areas employs a wide range of works and practices, among which are those that have adverse effects in the form of vibrations and shocks. This paper presents a theoretical study and original results concerning the seismic load on historical and dilapidated buildings in brownfield areas due to the ground-borne vibration caused by mechanized construction works. Original data from seismic measurements are related to the post-industrial Ostrava agglomeration, in the area of one of the biggest successfully revitalized brownfields in Central Europe. All measurements were evaluated in terms of both amplitude and frequency. The results of all measurements were processed in the form of attenuation curves.

Ground vibrations are commonly observed by using a standard seismic station equipped with speed seismometers or acceleration seismometers. The seismometers include three mechanical vibrating systems (sensors) and the primary output is the wave pattern of recording velocity or acceleration of the material point oscillation. An alternative new method how it is possible to realize seismic measurements is using of the fiber-optic interferometric sensors. These interferometers are well-known for their ability to make high-precision measurements of optical path difference or changes that may be induced by a refractive index change in the interferometer or a physical displacement. The paper presents a comparison of the results of the standard seismic measurement by using seismic station and of the fiber-optic interferometric sensor. As a source of dynamic load, truck transport was chosen. When trucks passing through unevenness on the road (due to the road damage, the transition area of the bridge etc.), it generates vibrations that are transmitted to the subsoil and can adversely affect the surrounding building objects. Data comparison of the subsoil dynamic response obtained during both approaches of measurements is present in the amplitude and primary in the frequency domain.

This article describes vehicle detection sensor based on optical fibre bending. Initial measurements were performed on a Heckert FP 10/1 press. Based on these measurements, a prototype of a bending sensor for vehicle detection was designed. This prototype is intended primarily for static vehicle detection, where the magnitude of attenuation is proportional to the weight of the car. When measuring on this prototype, we tested 4 types of ethylene propylene diene methylene (EPDM) grooved rubber that pressed on an optical fibre located on smooth EPDM rubber base. Based on the measurements, we chose the EPDM rubber cover for which the detector had the greatest sensitivity. These initial results indicate that this can be a life-capable structure with a possible extension to a static weight sensor and, partly, to a WIM (weigh in motion) dynamic weight sensor.

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